The Third Generation Partnership Project (3GPP) has initiated the Long Term Evolution (LTE) program to bring new technology, new network architecture, new configurations and new applications and services to wireless cellular networks in order to provide improved spectral efficiency and faster user experiences.
In order for a wireless transmit receive unit (WTRU) to perform various procedures related to sleep, monitoring the paging cycles, cell reselection or using a random access channel (RACH), a network would typically signal a number of parameters to the WTRU in system information messages. Some of these parameters can also be used when the WTRU is in an active state, including, but not limited to, reduced neighbor cell lists, measurement reporting and handover parameters. There is a need to put all necessary parameters together and group them into system information messages for use by the WTRU in procedures and methods for sleep, reselection or RACH procedures.
Within a core network (CN) domain system information, information for a discontinuous reception (DRX) would typically be signaled to a WTRU in idle mode in an information element (IE) (e.g., CN_DRX_cycle_length_coefficient). However, DRX exists in active mode as well as idle mode. Therefore, it would be beneficial to signal a DRX cycle length for the active mode.
When a WTRU is camped on a cell, it regularly searches for a better cell according to a set of criteria. If a better cell is found, that cell is selected. In an LTE system with only two states LTE_Idle and LTE_active, the WTRU can perform cell reselection only in the LTE_Idle state. The WTRU uses parameters broadcasted from the system, including, but not limited to the following parameters that are transmitted in a system information block (SIB), such as SIB 3, SIB 4 and/or SIB 11:                Qhyst1s: Used in ranking serving cell based on RSCP.        Qhyst2s: Used in ranking serving cell based on Ec/Io.        Qqualmin: Minimum required quality measure based on Ec/Io.        Qrxlevmin: Minimum required quality measure based on a received signal power measurement (e.g., received signal code power (RSCP)).        DeltaQrxlevmin: (conditional on value Delta) If present, the actual value of Qrxlevmin+DeltaQrxlevmin.        UE_TXPWR_MAX_RACH: Maximum allowed uplink (UL) TX power        Sintrasrch (optional): Measure intra-frequency neighbor cells when Squat≦Sintrasearch, where Squal is based on measured signal to interference ration of a corresponding cell measured by the WTRU minus Qqualmin.        Sintersrch (optional): Measure inter-frequency neighbor cells when Squal≦Sintersearch.        SsearchHCS (optional): Measure inter-Hierarchal Cell Structure (HCS)/inter-frequency neighbor cells when Squal≦SsearchHCS.        SHCS,RAT (optional): Measure inter-Hierarchal Cell Structure (HCS)/RAT neighbor cells when Squal≦SHCS,RAT.        Slimit,SearchRAT (optional): This threshold is used in the measurement rules for cell reselection when HCS is used. It specifies the RAT specific threshold (in dB) in the serving UTRA cell above which the UE may choose to not perform any inter-RAT measurements in RAT “m”.        